During takeoff, an aircraft reaches high speeds and as such, the wheels of the aircraft also rotate at a high rate of speed. Once the aircraft takes off, the wheels begin to “spindown.” Spindown is known in the art as the natural deceleration of the wheels after takeoff. After the wheels have sufficiently spundown, the wheels (along with the landing gear) are typically retracted and stored within the landing gear bay in the aircraft fuselage.
If a brake on a wheel is dragging (i.e., is at least partially engaged), then the brake may heat itself and/or other landing gear and/or wheel components to a very high temperature. The brakes may drag for a number of reasons, including over pressurization of the brake, a parked brake that is too hot because it has not cooled sufficiently after a previous landing and corresponding brake engagement, a broken brake rotor/stator, an improper brake adjustment, ice wedged between the pressure plate of the brake and the actuator, and the like. Brake dragging and the resulting heat are undesirable because, if the wheel and brake are retracted into the bay while hot, there may be an increased risk of failure (for example, the tire may rupture and expel a portion of the tire or wheel through the fuselage, damaging the aircraft). Accordingly, it is desirable to determine whether a brake is dragging in order to implement an appropriate response.